Article of Footwear

ABSTRACT

An article of footwear may include a polymer foam shell. The shell may include a midsole zone and an upper zone. An interior region of the shell may be defined by interior surfaces of the midsole zone and by interior surfaces of the upper zone. The article may further include a polymer foam inner midsole that is separate from and contained within the shell.

BACKGROUND

Conventional articles of footwear typically include two primary elements, namely, an upper and a sole structure. The upper may provide a covering for the foot that securely receives and positions the foot with respect to the sole structure. In addition, the upper may have a configuration that protects the foot. The sole structure is secured to a bottom surface of the upper and generally is positioned between the foot and a contact surface. In addition to attenuating ground reaction forces and absorbing energy, the sole structure may provide traction and control potentially harmful foot motion, such as excessive pronation. The general features and configurations of the upper and the sole structure are discussed in greater detail below.

An upper typically forms a void on the interior of the footwear for receiving the foot of a wearer. The void has the general shape of the foot, and access to the void may be provided at an ankle opening. The upper normally extends over the instep and toe areas of the foot, along the medial and lateral sides of the foot, and around the heel area of the foot. A lacing system often is incorporated into the upper to selectively change the size of the ankle opening and to permit the wearer to modify certain dimensions of the upper, particularly girth, to accommodate feet with varying proportions. In addition, an upper may include a tongue that extends under the lacing system to enhance the comfort of the footwear, e.g., to moderate pressure applied to the foot by the laces.

A sole structure generally incorporates multiple layers that are conventionally referred to as an insole, a midsole, and an outsole. The insole (which also may constitute a sock liner) is a thin member located within the upper and adjacent the plantar (lower) surface of the foot to enhance footwear comfort, e.g., to wick away moisture and provide a soft, comfortable feel. The midsole, which is traditionally attached to the upper along the entire length of the upper, forms the middle layer of the sole structure and serves a variety of purposes that can include controlling foot motions and attenuating impact forces. The outsole forms a ground-contacting element of footwear and is usually fashioned from a durable, wear-resistant material that may include texturing or other features to improve traction.

The primary element of a conventional midsole is a resilient, polymer foam material, such as polyurethane or ethylvinylacetate (“EVA”), that extends throughout the length of the footwear. The properties of the polymer foam material in a midsole are primarily dependent upon factors that include the dimensional configuration of the midsole and the specific characteristics of the material selected for the polymer foam, including the density of the polymer foam material. By varying these factors throughout the midsole, the relative stiffness, degree of ground reaction force attenuation, and energy absorption properties may be altered to meet the specific demands of the activity for which the footwear is intended to be used.

An ongoing need remains for improved footwear models and improved footwear constructions.

SUMMARY

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the invention.

In some embodiments, an article of footwear may include a polymer foam shell. The shell may include a midsole zone and an upper zone. An interior region of the shell may be defined by interior surfaces of the midsole zone and by interior surfaces of the upper zone. The article may further include a polymer foam inner midsole that is separate from and contained within the shell.

In at least some additional embodiments, an article of footwear may include a polymer foam shell that includes a midsole zone and an upper zone, and that further includes an interior region defined by interior surfaces of the midsole zone and by interior surfaces of the upper zone. The shell may further include a single main opening, the single main opening having a rear portion forming an ankle opening and a front portion forming an instep gap. A tongue may span the instep gap and form at least a portion of a waterproof barrier in the instep gap. The shell may lack any openings in regions below the waterproof barrier in the instep gap.

In at least some further embodiments, an article of footwear may include a polymer foam shell that includes a midsole zone and an upper zone, and that further includes an interior region defined by interior surfaces of the midsole zone and by interior surfaces of the upper zone. The upper zone may include a toe section, a medial side section and a lateral side section, the medial and lateral side sections extending rearward from the toe section and merging in a heel region. The medial side section may extend upward from medial side edges of the midsole zone to medial edges of an instep gap and of an ankle opening. The lateral side section may extend upward from lateral side edges of the midsole zone to lateral edges of the instep gap and of the ankle opening. The shell may further comprise a plurality of billows defined in exterior surfaces of the upper zone.

Additional embodiments are described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements.

FIG. 1A is a medial side view of an article of footwear according to some embodiments.

FIG. 1B is a lateral side view of the article of footwear of FIG. 1A.

FIG. 1C is a front top perspective view of the article of footwear of FIG. 1A.

FIG. 1D is a rear view of the article of footwear of FIG. 1A.

FIG. 1E is a bottom view of the article of footwear of FIG. 1A.

FIG. 2 is a partially schematic area cross-sectional view taken from the location indicated in FIG. 1A.

FIG. 3A is a medial side view of an internal midsole of the article of footwear of FIG. 1A.

FIG. 3B is a lateral side view of an internal midsole of the article of footwear of FIG. 1A.

DETAILED DESCRIPTION

In at least some embodiments, an article of footwear may include a polymer foam shell that serves as an upper and as at least part of a sole structure. In particular, the shell may have a midsole zone and an upper zone. The midsole zone may be situated between the article interior and the ground and may provide cushioning and support to a wearer foot. The upper zone may extend upward from midsole zone and, in combination with the midsole zone, form a foot-receiving interior void of the article. The midsole and upper zones may be integral parts of a unitary polymer foam boot structure. More specifically, the shell may be a single piece of polymer foam material having an interior void with a shape that approximates a human foot. The midsole zone may constitute a bottom portion of the shell and the upper zone may constitute a top portion of the shell. In some embodiments the boot structure may be an over-ankle or “high top” design configured to extend over a wearer ankle. In other embodiments the boot structure may be a below-ankle or “low top” design configured to not extend over a wearer ankle. The article of footwear may further include an outsole on a bottom of the midsole zone. That outsole and the midsole zone may form an external portion of a sole structure for the article.

In some embodiments, the article of footwear may further include a separate internal midsole located within the shell. That internal midsole and the external sole structure may form the complete sole structure for the article. The internal midsole may also be a polymer foam element. In at least some embodiments, the polymer foam of the internal midsole is less dense than the polymer foam of the shell. A full or partial foot contacting element, i.e., an internal “bootie,” may also be located within the shell and may serve as a full or partial lining. In some embodiments, the internal midsole may be located within the bootie, while in other embodiments the internal midsole may be situated between a bottom of the bootie and a top of the midsole zone.

In some embodiments, an article of footwear such as is described above is configured for use as a rain shoe or for wear in other wet environments. In at least some such embodiments, the shell may be formed of a polymer foam material through which water will not penetrate, e.g., the polymer foam may be a closed cell polymer foam. That shell may have a single main opening in the top of the upper zone. A portion of that main opening may form an ankle opening through which a wearer foot is inserted. Another portion of that main opening may form an instep region gap. A tongue may span the instep region gap and be attached to the shell with gussets at or near interior edges of the instep region gap. The shell may lack any additional openings below edges of a waterproof barrier formed by (or that includes) the tongue. The tongue and gussets may be formed from a material that is impenetrable by water. In other embodiments in which an article of footwear is intended for use in wet environments, the shell may have one or more ventilation openings, with those ventilation openings covered by a material that resists water penetration but that allows air flow. A tongue may similarly be formed from a breathable material that resists water penetration.

These and other embodiments are described in more detail below. To assist and clarify subsequent description of various embodiments, various terms are defined herein. Unless context indicates otherwise, the following definitions apply throughout this specification (including the claims). “Shoe” and “article of footwear” are used interchangeably to refer to articles intended for wear on a human foot. A shoe may or may not enclose the entire foot of a wearer. For example, a shoe could include a sandal or other article that exposes large portions of a wearing foot. The “interior” of a shoe refers to space that is occupied by a wearer's foot when the shoe is worn. An interior side, surface, face or other aspect of a shoe element refers to a side, surface, face or other aspect of that element that is (or will be) oriented toward the shoe interior in a completed shoe. An exterior side, surface, face or other aspect of an element refers to a side, surface, face or other aspect of that element that is (or will be) oriented away from the shoe interior in the completed shoe. In some cases, the interior side, surface, face or other aspect of an element may have other elements between that interior side, surface, face or other aspect and the interior in the completed shoe. Similarly, an exterior side, surface, face or other aspect of an element may have other elements between that exterior side, surface, face or other aspect and the space external to the completed shoe.

Unless the context indicates otherwise, “top,” “bottom,” “over,” “under,” “above,” “below,” and similar locational terms assume that a shoe or shoe structure of interest is in the orientation that would result if the shoe (or shoe incorporating the shoe structure of interest) is in an undeformed condition with its outsole (and/or other ground-contacting sole structure element(s)) resting on a flat horizontal surface. Unless the context requires otherwise, however, the term “upper” is reserved for use in describing the portion of a shoe that at least partially covers the sides and top of a wearer foot and that helps to secure the wearer foot to a shoe sole structure.

Elements of a shoe can be described based on regions and/or anatomical structures of a human foot wearing that shoe, and by assuming that shoe is properly sized for the wearing foot. As an example, a forefoot region of a foot includes the metatarsal and phalangeal bones. A forefoot element of a shoe is an element having one or more portions located over, under, to the lateral and/or medial sides of, and/or in front of a wearer's forefoot (or portion thereof) when the shoe is worn. As another example, a midfoot region of a foot includes the cuboid, navicular, medial cuneiform, intermediate cuneiform and lateral cuneiform bones and the heads of the metatarsal bones. A midfoot element of a shoe is an element having one or more portions located over, under and/or to the lateral and/or medial sides of a wearer's midfoot (or portion thereof) when the shoe is worn. As a further example, a heel region of a foot includes the talus and calcaneus bones. A heel element of a shoe is an element having one or more portions located over, under, to the lateral and/or medial sides of, and/or behind a wearer's heel (or portion thereof) when the shoe is worn. The forefoot region may overlap with the midfoot region, as may the midfoot and heel regions.

Unless indicated otherwise, a longitudinal axis refers to a horizontal heel-toe axis along the center of a shoe and that is roughly parallel to a line that would follow along the second metatarsal and second phalanges of a wearer foot. A transverse axis refers to a horizontal axis across a shoe that is generally perpendicular to a longitudinal axis. A longitudinal direction is parallel (or roughly parallel) to a longitudinal axis. A transverse direction is parallel (or roughly parallel) to a transverse axis.

FIG. 1A is a medial side view of a shoe 100 according to some embodiments. As can be appreciated from FIG. 1A, shoe 100 is a right foot shoe. Shoe 100 is part of a pair that includes a left foot shoe (not shown) that is a mirror image of shoe 100. FIG. 1B is a lateral side view of shoe 100. FIG. 1C is a front top perspective view of shoe 100. FIG. 1D is a rear view of shoe 100. FIG. 1E is a bottom view of shoe 100.

Components of shoe 100 visible in FIGS. 1A-1E include a shell 101, an outsole 102 and a bootie 103. Although not visible in FIGS. 1A-1E, shoe 100 further includes an internal midsole 201. Bootie 103 and internal midsole 201 are further described below in connection with subsequent drawing figures.

In the embodiment of shoe 100 and in at least some other embodiments, shell 101 is a unitary polymer foam boot structure. More specifically, shell 101 is a single piece of polymer foam material having an interior void with a shape that approximates a human foot. The bottom of shell 101 is closed and provides a layer of the shell polymer foam between the bottom of a wearer foot and the ground or other contact surface. The top of shell 101 wraps around the sides, rear and top forefoot regions of a wearer foot. A separate outsole 102, discussed more fully below, is located on the bottom of shell 101 and in the front of shell 101.

Shell 101 includes a single main opening 105. A rear portion of main opening 105 forms an ankle opening 106 (FIGS. 1A and 1B). Ankle opening 106 provides the opening through which a wearer foot may be inserted so as to don shoe 100. A front portion of main opening 105 forms an instep gap 107. Similar to conventional shoes, instep gap 107 provides a means by which the size of shoe 100 can be adjusted to accommodate variations in wearer foot width and/or thickness of a sock worn by a wearer. A tongue 108 spans instep gap 107. In the embodiment of shoe 100, a front exterior part of tongue 108 is attached to the interior of shell 101 forward of a front edge 120 of instep gap 107. Gussets, not shown, attach medial and lateral sides of tongue 108 to the interior of shell 101 below medial and lateral edges of instep gap 107. A lace 110 passes through lace holes 111 in shell 101 near edges of a front part of gap 107 and through separately attached eyelets 112 near edges of a rear part of gap 107. Lace 108 can be cinched so as to secure shoe 100 to a wearer foot.

Shell 101 acts as both an upper and as a midsole of shoe 100. Similar to a conventional midsole, a bottom portion of shell 101 provides a layer of foam to surround, support and cushion the plantar (bottom) and edge regions of a wearer foot. Similar to a conventional upper, a top portion of shell 101 covers and protects the front, top forefoot, sides and rear of the wearer foot and helps to secure the wearer foot relative to the bottom portion of shell 101. For convenience, the bottom and top portions of shell 101 are referred to herein as the “midsole zone” and the “upper zone” of shell 101.

A broken line L1 in FIGS. 1A, 1B and 1D indicates an approximate boundary between upper zone 114 and midsole zone 115. As indicated above, shell 101 is a single piece of polymer foam material. Upper zone 114 and midsole zone 115 merge seamlessly with each other. Accordingly, line L1 is not intended to not represent a seam or other discontinuity between upper zone 114 and midsole zone 115. Instead, line L1 merely indicates the approximate location of where the shell 101 polymer foam transitions from being a part of a shoe 100 sole structure to being a part of the shoe 100 upper. The location of a boundary between a midsole zone and an upper zone may vary in different embodiments.

A reinforcement strip 116 surrounds the exterior edge of main opening 105. Strip 116 may be cut or otherwise formed from synthetic leather, thermoplastic polyurethane (TPU), polyurethane (PU), vinyl or other material and may be stitched and/or or adhesively bonded and/or otherwise attached to shell 101. Strip 116 reinforces the edges of main opening 105 so as to help prevent tearing of the shell 101 foam material as a result of tension in lace 110 or abrasion of an exposed foam edge.

Upper zone 114 includes a medial side section 117 (FIGS. 1A and 1D), a lateral side section 118 (FIGS. 1B and 1D) and a toe section 119 (FIGS. 1A through 1C). For convenience, and as discussed below, FIGS. 1A through 1D includes broken lines L2, L3 and L4 to indicate approximate boundaries between these sections of upper zone 114. Similar to line L1, however, none of lines L2, L3 or L4 is intended to represent a seam or other discontinuity. In the embodiment of shoe 100 and in at least some other embodiments, toe section 119, medial side section 117 and lateral side section 118 merge seamlessly with one another. Locations of boundaries between sections of a shell upper zone may vary in different embodiments.

Toe section 119 is the portion of upper zone 114 forward of lines L2 and L3. Toe section 119 extends across and in front of the frontmost portion of the forefoot region and forms the frontmost section of upper zone 114. Toe section 119 merges with and extends upward from the sides and front of a corresponding frontmost forefoot region of midsole zone 115. In the embodiment of shoe 100, toe section 119 extends forward from the front edge 120 of gap 107 (FIG. 1C). Toe section 119 approximately corresponds to the region of a wearer foot forward of the metatarsal-phalangeal joints. When shoe 100 is worn, a toe box formed by toe section 119 and the frontmost forefoot region of midsole zone 115 completely surrounds the top, sides, bottom and front of that corresponding wearer foot region.

In the vertical direction, and as seen in FIGS. 1A and 1D, medial side section 117 extends upward from medial side edge and medial rear edge portions of midsole zone 115 to medial side edge and medial rear edge portions of main opening 105. In the horizontal direction, medial side section 117 extends from toe section 119 to lateral section 118 at the center of the rear of shell 101. Line L2 (FIG. 1A) indicates an approximate boundary between toe section 119 and medial side section 117. Line L4 (FIG. 1D) indicates an approximate boundary between medial side section 117 and lateral side section 118.

As seen in FIGS. 1B and 1D, lateral side section 118 extends vertically from the lateral side edge and lateral rear edge portions of midsole zone 115 to lateral side edge and lateral rear edge portions of main opening 105. In the horizontal direction, lateral side section 118 extends from toe section 119 to medial section 117 at the center of the rear of shell 101. Line L3 (FIG. 1B) indicates an approximate boundary between toe section 119 and lateral side section 118.

As seen in FIGS. 1A, 1B and 1D, shell 101 is a “high top” boot structure in which upper zone 114 is sized to extend over the ankle of a wearer. When worn, an edge of ankle opening 106 is positioned above the wearer's medial and lateral malleoli at peaks 121 (FIG. 1A) and 122 (FIG. 1B). Other embodiments include shells in which a boot structure is a “low top.” Stated differently, in some embodiments a shell boot structure includes an upper zone that does not extend over a wearer's ankle.

In at least some embodiments, upper zone 114 of shell 101 may have a billowed structure. Specifically, a plurality of billows 124 are formed in the exterior surfaces of upper zone 114. Billows 124 are peaks of ridges that are separated from one another so as to define valleys 125. In the embodiment of shoe 100 billows 124 include longitudinally oriented segments on medial side section 117 and lateral side section 118, as well as transversely oriented segments on toe section 119. Further, most of billows 124 and valleys 125 extend continuously around upper zone 114. In the embodiment of shoe 100, and as discussed in further detail below in connection with FIG. 2, billows are not formed on the interior surfaces of upper zone 114.

The billowed structure of upper zone 114 increases flexibility in the regions of valleys 125. For example, valleys 125 between billows 124 in toe section 119 reduce resistance of upper zone 114 to dorsiflexion of a wearer foot. Valleys 125 between billows 124 in ankle region portions of medial side section 117 and lateral side section 118 reduce resistance of upper zone 114 in response to medial or lateral tilting of a wearer ankle.

The billowed structure shown in FIGS. 1A-1D is merely exemplary. There are innumerable additional embodiments in which an upper zone may be functionally similar to upper zone 114 of shoe 100, but which may have a different visual appearance. For example, the number and size of billows could be varied. The precise arrangement of billows could also be varied. Shapes of billows could also be varied. Billows need not extend continuously around an entire upper component.

FIG. 1E shows additional details of outsole 102. In some embodiments, and so as to provide increased resistance to abrasion or other wear in ground contacting zones, at least some portions of outsole 102 are formed from one or more materials different from the polymer foam of shell 101. Examples of such other different materials include, without limitation, synthetic and natural rubbers, polymer foams having increased density or other characteristics to enhance wear resistance, non-foamed TPU, non-foamed PU and other non-foamed polymers. In the embodiment of shoe 100, outsole 102 includes a perimeter 126 formed of a first material and an inner region 127 formed by a second material. The first material may be harder than the second region. The harder first material provides increased wear resistance on the edges of outsole 102. The softer second material of inner region 127 provides enhanced slip resistance.

As indicated above, shoe 100 according to some embodiments is configured for wear in rain or other wet environments. So as to increase traction in wet conditions, perimeter 126 of outsole 102 includes a plurality of lugs 128 separated by gaps 129. At least a portion of lugs 128 also extend further downward than inner region 127. In this manner, gaps 129 provide channels for water to escape from under outsole 102 when a wearer steps into standing water, and thereby increase traction. A plurality of grooves 130 may also be formed in inner region 127 to increase traction. The arrangement of outsole 102 elements shown in FIG. 1E is also exemplary. There are innumerable additional embodiments in which a sole structure may include an outsole that is functionally similar to outsole 102 of shoe 100, but which may have a different visual appearance. For example, the number, size and arrangement of lugs and grooves could be varied. The precise arrangement of a perimeter relative to an inner region also be varied, as could other aspects of an outsole.

As seen in FIGS. 1A through 1C, outsole 102 includes a medial forefoot wing extension 131, a toe cap extension 132 and a lateral forefoot wing extension 133. Medial forefoot wing 131 extends upward and around the medial edge of midsole zone 115 in a location approximately corresponding to an end of a wearer first metatarsal. Lateral forefoot wing 133 extends upward and around the lateral edge of midsole zone 115 in a location approximately corresponding to an end of a wearer fifth metatarsal. Wings 131 and 133 help provide additional support and stability in response to sideways movements of a wearer. Toe cap 132 extends upward and around the front of midsole zone 115. Toe cap 132 provides further protection to the frontmost portion of shell 101 in response to contact with external objects (e.g., kicked objects).

Midsole zone 115 and outsole 102 form the external sole structure of shoe 100. This is further shown in FIG. 2, a partially schematic area cross-sectional view taken from the location indicated in FIG. 1A. Elements visible in FIG. 2 include shell 101, outsole 102, bootie 103 and strip 116. The approximate locations of upper zone 114 and midsole zone 115 are also indicated. An internal midsole 201, also shown in FIG. 2, is discussed in further detail below. For purposes of simplification and to avoid obscuring FIG. 2 with detail not needed to understand the relationship of shoe 100 elements, bootie 103 is represented in FIG. 2 as a solid line. For similar reasons, FIG. 2 includes small spaces between elements that may actually be in direct contact. In particular, some or all of the exterior of bootie 103 may be in contact with interior surfaces of shell 101. Similarly, some or all exterior surfaces of inner midsole 201 may be in contact with interior faces of bootie 103.

Outsole 102 is located on the bottom side of the midsole zone 115 exterior. As indicated above, and as seen more clearly in FIG. 2, outsole 102 and shell 101 are separate elements in the embodiment of shoe 100. If outsole 102 were removed, for example, the foam material in midsole zone 115 of shell 101 would still separate the plantar sides of bootie 102 and inner midsole 201 from the ground. In some embodiments, outsole 102 does not cover the entire bottom side of midsole zone 115. For example, and as seen in FIG. 1E, a medial midfoot region 136 of midsole zone 115 is exposed between front and rear lobes of outsole 102.

Returning to FIG. 2, midsole zone 115 includes an interior base surface 202, an interior medial lower side surface 203 and an interior lateral lower side surface 204. Interior base surface 202 extends the full length and width of the shell 101 interior. Medial lower side surface 203 and lateral lower side surface 204 extend the full length of the shell 101 interior to wrap around and meet in the front and rear of the shell 101 interior. Base surface 202, interior medial lower side surface 203 and interior lateral lower side surface 204 define the bottom portion of the shell 101 interior.

The top portion of the shell 101 interior is defined by an interior surface (not shown) of toe section 119, a medial side section interior surface 205 and a lateral side section interior surface 206. Medial side section interior surface 205 extends vertically from medial lower side surface 203 to the edge of main opening 105. Lateral side section interior surface 206 extends vertically from lateral lower side surface 204 to the edge of main opening 105. In the horizontal direction, medial side section interior surface 205 and lateral side section interior surface 206 extend rearward from the interior surface of toe section 119, around the rear of the shell 101 interior, and meet along an interior line corresponding to line L4 of FIG. 1D. In the embodiment of shoe 100, the interior surfaces of shell 101 are smooth.

Inner midsole 201 is located inside bootie 103 and fits snugly in the bottom of the shell 101 interior. Inner midsole 201 may also be a polymer foam element. Inner midsole 201 may be sized and shaped to have an interior surface 207 that conforms to and supports the entire plantar surface of a wearer foot. Edge surfaces 208 and 209 may be sized to conform to and support edges of a wearer foot. In at least some embodiments, and as discussed in more detail below, the polymer foam of inner midsole 201 may be softer and/or less dense than the polymer foam of shell 101.

FIGS. 3A and 3B are respective medial and lateral side views of inner midsole 201. So as to generally show the position of inner midsole 201 within shoe 100, shell 101 is approximately indicated with a broken line silhouette. Edge surfaces 208 and 209 may extend the length of inner midsole 201 and around the rear of inner midsole 201. In the rear, edge surfaces 208 and 209 meet and form a heel cup 210. On the medial side, a midfoot portion of edge surface 208 is enlarged to be an arch support 211. Returning briefly to FIG. 2, a thickness t of inner midsole 201 is shown. Thickness t in one or more areas of the heel and/or midfoot regions of inner midsole 201 may be greater than thickness t in one or more areas of the inner midsole 201 forefoot region. In some embodiments, and as partially seen in FIGS. 3A and 3B, base surface 207 and edge surfaces 208 and 209 may have may have a pattern formed thereon so as to increase friction relative to the socked foot of a shoe 100 wearer. The pattern shown is only exemplary, however, and other patterns could be used.

In some embodiments, bootie 103 may be removable, while in other embodiments bootie 103 may be glued (in whole or in part) to interior surfaces of shell 101. Numerous materials or combinations of materials can be used for bootie 103. As but one example, side and top portions of bootie 103 could be a knitted spacer mesh material and the bottom of bootie 103 could be a woven Strobel or other lasting element. The lasting element edges could be stitched or otherwise joined to lower edges of the knitted spacer mesh element(s). In some embodiments, bootie 103 may line substantially all of the interior of shell 101 but may include an instep region gap so as not to overlap with tongue 108.

In at least some embodiments, the polymer foam of shell 101 is selected from the group that includes ethylvinylacetate (EVA) foam, polyurethane foam and phylon foam. In at least some of these and other embodiments, the shell 101 polymer foam may have a density higher than the density of the foam material of inner midsole 201. As more specific examples, shell 101 may be an ethylvinylacetate foam material, a polyurethane foam material, and/or a phylon foam material having a density greater than 0.2 g/cm³, and in some examples, a density of greater than 0.25 g/cm³, and in some further examples, having a density within a range of 0.25 g/cm³ to 1 g/cm³ or even within the range of 0.25 g/cm³ to 0.75 g/cm³. The polymer foam of shell 101 could be a material like the shell material described in U.S. Pat. No. 7,941,938 (which patent is incorporated by reference herein). The polymer foam of shell 101 at one location may differ from the polymer foam at another location (e.g., with regard to density, hardness, abrasion resistance, color, thickness, etc.) to provide desired properties at desired locations.

Examples of polymer foams for inner midsole 201 include, without limitation, EVA foam, polyurethane foam, phylon foam, and phylite foam. As further examples, inner midsole 201 may be at least partially made from a foam material having a density of less than 0.25 g/cm³ (and in some examples, a density of less than 0.2 g/cm³, within the range of 0.075 to 0.2 g/cm³, and even within the range of 0.1 to 0.18 g/cm³). If desired, the inner midsole 201 foam material may include one or more openings defined therein and/or another impact-force attenuating component, such as a fluid-filled bladder, included therein. In certain embodiments, inner midsole 201 will constitute lightweight foam material (e.g., with a density feature as described above) and will extend to support the complete foot of the wearer (e.g., the complete plantar surface). Alternatively, inner midsole 201 may comprise multiple inner midsole components. One or more of those components may have one or more properties (e.g., density) that differ from properties of another of those components.

As a further example, inner midsole 201 may be made from a foam material as described, for example, in U.S. Pat. No. 7,941,938. In at least some embodiments, all, substantially all, or at least some portion of inner midsole 201 may include a foam material comprising a reaction product of about 10 to about 100 parts per hundred hydrogenated or non-hydrogenated acrylonitrile butadiene copolymer, 0 to about 40 parts per hundred modified hydrogenated acrylonitrile butadiene copolymer, and 0 to about 90 parts per hundred alpha olefin copolymer, and at least one additive in an amount suitable to form the foam material. This foam material may have a lightweight, spongy feel. The density of the foam material may be generally less than 0.25 g/cm³, less than 0.20 g/cm³, less than 18 g/cm³, less than 0.15 g/cm³, less than 0.12 g/cm³, and in one aspect, about 0.10 g/cm³. As example ranges, the foam density may fall within the range, for example, of 0.05 to 0.25 g/cm³ or within the various ranges noted above.

Also, in accordance with at least some embodiments, the resiliency of the foam material for inner midsole 201 may be greater than 40%, greater than 45%, at least 50%, and in one aspect from 50-70%. Compression set may be 60% or less, 50% or less, 45% or less, and in some instances, within the range of 20 to 60%. The hardness (Durometer Asker C) of the foam material for this example inner midsole 201 may be, for example, 25 to 50, 25 to 45, 25 to 35, or 35 to 45, e.g., depending on the type of footwear. The tensile strength of the foam material for inner midsole 201 may be at least 15 kg/cm², and typically 15 to 40 kg/cm². The elongation % may be 150 to 500, typically above 250. The tear strength may be 6-15 kg/cm, typically above 7. In at least some embodiments, the foam material of at least some portion of inner midsole 201 may have lower energy loss and may be more lightweight than traditional EVA foams. The energy loss may be less than 30%, and optionally within the range of about 20% to about 30%. As additional examples, if desired, at least some portion of inner midsole 201 may be made from foam materials used in the LUNAR family of footwear products available from NIKE, Inc. of Beaverton, Oreg.

In at least some embodiments, some or all of the shell 101 polymer foam may have a density at least 10% greater than the density of the inner midsole 201 polymer foam. In some embodiments some or all of the shell 101 polymer foam may have a density at least 25% greater, at least 50% greater, at least 100% greater, or even at least 200% greater than the density of the inner midsole 201 polymer foam.

In some embodiments, midsole 201 polymer foam may be an EVA foam having properties in ranges such as are listed in Table 1.

TABLE 1 Property Unit Min. Max. expansion ratio (mold % 189 191 cavity size to finished component size) hardness (Asker C) n/a 36 40 specific gravity gr/cc 0.1 0.12 split tear strength kg/cm 1.2 compression set % 60 tensile strength kg/cm³ 14 elongation % 250 tear strength kg/cm 7 shrinkage % 2 resiliency % 45

In at least some embodiments, shell 101 is molded as a single piece. Outsole 102, which may be separately molded or otherwise formed as a single piece or as multiple pieces, is then attached to shell 101 with adhesive, by thermal bonding, by mechanical fasteners and/or using other attachment mechanisms. In some embodiments, an outsole may be integrally formed with a shell through dual density molding or other technique.

Shoe 100 according to some embodiments is intended for wear during rain or in other wet conditions, and thus is configured to prevent water from reaching the shoe 100 interior from the outside. In at least some such embodiments, shell 101 may have a single main opening (i.e., main opening 105) in the top of upper zone 114. With the exception of lace holes 111 and holes filled by fasteners for eyes 112, shell 101 may lack any other openings below the edge of main opening 105. Shell 101 may be formed from a polymer foam through which water will not penetrate, e.g., a closed cell polymer foam such as one of the types of foam described above. Tongue 108 also resists water penetration and spans the instep gap 107 portion of main opening 105 below lace holes 111 and attachment holes of eyelets 112, thereby forming at least a portion of a waterproof barrier in instep gap 107. Medial and lateral sides of tongue 108 could be attached to medial and lateral side edges of instep gap 107 with waterproof gussets, which gussets could be part of tongue 107 or could be separate elements. The waterproof barrier in instep gap 107, combined with the lack of shell 101 openings below that barrier, prevents water incursion into shell 101.

In some embodiments, shell 101 may include apertures, vents or other openings in lower portions of upper zone 114. Such other openings could be left open. Alternatively, pieces of breathable waterproof or water-resistant material could be glued over one or more of those other openings so as to permit perspiration moisture to escape from the shoe interior but prevent water reaching the interior from the outside. Tongue 108 could also comprise a breathable waterproof or water-resistant material.

Additional embodiments include numerous variations on one or more of the features described thus far. In some embodiments, for example, an inner midsole may not be located within a bootie as shown in FIG. 2. In some such embodiments, an inner midsole may be located directly on the bottom of the shell interior and the bootie bottom may rest on top of the inner midsole, i.e., the internal midsole may be situated between a bottom of the bootie and a top of a midsole zone of the shell. In other embodiments, a first inner midsole may be located between the shell and the bootie and a second inner midsole may be located within the bootie.

An inner midsole need not extend under the entire plantar surface of a wearer foot. For example, an inner midsole could be limited to heel and/or midfoot regions of a shell interior. An inner midsole could be nondestructively removable from a shoe. Alternatively, an inner midsole could be glued or otherwise secured within a shoe.

A shell and/or an inner midsole could include additional components. For example, non-foam stiffening elements could be embedded in a shell during the molding process so as to provide additional support and/or protection in certain regions. Examples of elements that might be embedded include, without limitation, protective covers in a toe region, a counter in a heel region, a protective plate in an ankle region and a support plate in an arch region. As further examples, reinforcing rods could be embedded in a midsole zone of a shell and/or in an inner midsole. A cavity could be created in a shell and/or in an inner midsole during the molding process, which cavity could then hold a fluid filled cushioning bladder.

Other types of outsole elements and/or other patterns of elements could be included in addition to or instead of the elements and patterns shown for outsole 102. Additional types of outsole elements that might be included in other embodiments include lugs having cone, truncated cone, pyramid, truncated pyramid or other type of shape, cleats or other type of traction elements, etc.

In at least some embodiments, shell 101 is a unitary and substantially homogeneous polymer foam boot structure. In addition to lacking seams or discontinuities, the polymer foam may be of consistent properties throughout substantially the entire structure (e.g., throughout the entire structure except for a thin skin on the interior and exterior surfaces). In other embodiments, shell 101 may be a non-unitary polymer foam boot structure and may be non-homogeneous. For example, a portion of a boot structure may be formed from a first type of polymer foam. Gaps may be formed in the first polymer foam during molding and/or by cutting after molding. One or more of those gaps may then be filled with a second type of polymer foam. The second polymer foam may be lighter and the gaps filled by the second polymer foam may be in regions of the boot subject to lesser stress during shoe wear. In some embodiments, upper and midsole zones of a shell may be formed separately and then bonded or otherwise joined.

The foregoing description of embodiments has been presented for purposes of illustration and description. The foregoing description is not intended to be exhaustive or to limit embodiments of the present invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of various embodiments. The embodiments discussed herein were chosen and described in order to explain the principles and the nature of various embodiments and their practical application to enable one skilled in the art to utilize the present invention in various embodiments and with various modifications as are suited to the particular use contemplated. Any and all combinations, subcombinations and permutations of features from above-described embodiments are the within the scope of the invention. With regard to claims directed to an apparatus, an article of manufacture or some other physical component or combination of components, a reference in the claim to a potential or intended wearer or a user of a component does not require actual wearing or using of the component or the presence of the wearer or user as part of the claimed component or component combination. 

1. An article of footwear, comprising: a polymer foam shell having a midsole zone and an upper zone, the shell having an interior region defined by interior surfaces of the midsole zone and by interior surfaces of the upper zone; and a polymer foam inner midsole separate from and contained within the shell.
 2. The article of footwear of claim 1, wherein the midsole zone and the upper zone are portions of a unitary polymer foam boot structure.
 3. The article of footwear of claim 1, further comprising an outsole located on at least a bottom of the midsole zone.
 4. The article of footwear of claim 1, wherein the upper zone includes a toe section extending across and in front of a forefoot region to form, in conjunction with a corresponding portion of the midsole zone, an enclosed toe box.
 5. The article of footwear of claim 4, wherein the upper zone includes medial and lateral side sections, the medial and lateral side sections extend rearward from the toe section and merge in a heel region, the medial side section extends upward from medial side edges of the midsole zone to medial edges of an instep gap and of an ankle opening, and the lateral side section extends upward from lateral side edges of the midsole zone to lateral edges of the instep gap and of the ankle opening.
 6. The article of footwear of claim 5, further comprising a plurality of billows defined in exterior surfaces of the upper zone.
 7. The article of footwear of claim 6, wherein the billows include longitudinally oriented segments on the medial and lateral side sections and transversely oriented segments on the toe section.
 8. The article of footwear of claim 7, wherein the billows extend continuously around the upper zone.
 9. The article of footwear of claim 1, wherein a density of the shell polymer foam is at least 25% greater than a density of the inner midsole polymer foam.
 10. The article of footwear of claim 1, further comprising a bootie located within the shell, wherein the inner midsole is located within the bootie.
 11. The article of footwear of claim 10, wherein the inner midsole extends substantially the entire length and width of a bottom of an interior of the shell, the inner midsole includes heel, midfoot and forefoot sections, a thickness of the heel section is greater than a thickness of the forefoot section.
 12. The article of footwear of claim 11, wherein a medial side of the inner midsole midfoot section includes a raised arch region support.
 13. The article of footwear of claim 1, wherein the shell includes a single main opening, the single main opening having a rear portion forming an ankle opening and a front portion forming an instep gap, the article further comprises comprising a tongue spanning the instep gap and forming at least a portion of a waterproof barrier in the instep gap, and the shell lacks any openings in regions below the waterproof barrier.
 14. An article of footwear, comprising: a polymer foam shell having a midsole zone and an upper zone, the shell having an interior region defined by interior surfaces of the midsole zone and by interior surfaces of the upper zone, and wherein the shell includes a single main opening, the single main opening having a rear portion forming an ankle opening and a front portion forming an instep gap, the article further comprises comprising a tongue spanning the instep gap and forming at least a portion of a waterproof barrier in the instep gap, and the shell lacks any openings in regions below the waterproof barrier.
 15. The article of footwear of claim 14, wherein the upper zone includes a toe section, a medial side section and lateral side section, the medial and lateral side sections extend rearward from the toe section and merge in a heel region, the medial side section extends upward from medial side edges of the midsole zone to medial edges of the instep gap and of the ankle opening, the lateral side section extends upward from lateral side edges of the midsole zone to lateral edges of the instep gap and of the ankle opening, and the shell further comprises a plurality of billows defined in exterior surfaces of the upper zone.
 16. The article of footwear of claim 15, wherein the billows include longitudinally oriented segments on the medial and lateral side sections and transversely oriented segments on the toe section.
 17. The article of footwear of claim 14, further comprising an outsole located on at least a bottom of the midsole zone.
 18. An article of footwear, comprising: a polymer foam shell having a midsole zone and an upper zone, the shell having an interior region defined by interior surfaces of the midsole zone and by interior surfaces of the upper zone, and wherein the midsole zone and the upper zone are portions of a unitary polymer foam boot structure, and the upper zone includes a toe section extending across and in front of a forefoot region to form, in conjunction with a corresponding portion of the midsole zone, an enclosed toe box.
 19. The article of footwear of claim 18, wherein the upper zone includes a medial side section and a lateral side section, the medial and lateral side sections extend rearward from the toe section and merge in a heel region, the medial side section extends upward from medial side edges of the midsole zone to medial edges of an instep gap and of an ankle opening, the lateral side section extends upward from lateral side edges of the midsole zone to lateral edges of the instep gap and of the ankle opening, and the shell further comprises a plurality of billows defined in exterior surfaces of the upper zone.
 20. The article of footwear of claim 19, wherein the billows include longitudinally oriented segments on the medial and lateral side sections and transversely oriented segments on the toe section.
 21. The article of footwear of claim 18, further comprising an outsole located on at least a bottom of the midsole zone.
 22. An article of footwear, comprising: a polymer foam shell having a midsole zone and an upper zone, the shell having an interior region defined by interior surfaces of the midsole zone and by interior surfaces of the upper zone, and wherein the upper zone includes a toe section, a medial side section and lateral side section, the medial and lateral side sections extend rearward from the toe section and merge in a heel region, the medial side section extends upward from medial side edges of the midsole zone to medial edges of an instep gap and of an ankle opening, the lateral side section extends upward from lateral side edges of the midsole zone to lateral edges of the instep gap and of the ankle opening, and the shell further comprises a plurality of billows defined in exterior surfaces of the upper zone.
 23. The article of footwear of claim 22, wherein the billows include longitudinally oriented segments on the medial and lateral side sections and transversely oriented segments on the toe section.
 24. The article of footwear of claim 22, wherein the midsole zone and the upper zone are portions of a unitary polymer foam boot structure, and the toe section forms, in conjunction with a corresponding portion of the midsole zone, an enclosed toe box.
 25. The article of footwear of claim 22, wherein the shell includes a single main opening, the single main opening having a rear portion forming the ankle opening and a front portion forming the instep gap, the article further comprises comprising a tongue spanning the instep gap and forming at least a portion of a waterproof barrier in the instep gap, and the shell lacks any openings in regions below the waterproof barrier. 